Chloroform

One way chloroform enters the body is by inhalation
of contaminated air into the lungs. Chloroform is absorbed readily
into the body when inhaled. Chloroform can quickly enter the blood
stream from the lungs or intestines. Once in the blood, it is carried
to all parts of the body, such as the liver or kidneys. Chloroform
usually collects in body fat and is metabolized in the kidney and
excreted through the lungs (unchanged) or through the urine and
feces. Some of the chloroform that enters the body is broken down
into other chemicals. These chemicals, or breakdown products, can
attach to other chemicals inside the cells of the body and may cause
harmful effects if they collect in high enough amounts in the body.
Some of the breakdown products can also leave the body through exhaled
air. Only a small amount of the breakdown products leaves the body
in the urine or feces (ATSDR, 1995).

Exposure to chloroform in the environment from
the ambient air is a health concern because of a potential to induce
cancer from chronic exposure and possible additivity with other
sources of chloroform in daily life. In humans, large amounts of
inhaled chloroform can affect the central nervous system (brain),
liver, and kidneys. At very high concentrations chloroform has been
used as an anesthetic agent in man. This use was discontinued as
safer agents became available. Breathing about 900 ppm (4000 ug/m
3 ) for a short time causes fatigue, dizziness, and headache. At
lesser concentrations over a long period of time, chloroform may
damage the liver and kidneys. At lesser concentrations chloroform
has produced reproductive effects in animals such as birth defects
and abnormal sperm. It is not known whether these effects would
occur in humans.

Most chloroform in the air eventually breaks
down, but this process is slow. The breakdown products in air include
phosgene, which is more toxic than chloroform, and hydrogen chloride,
which is also toxic (ATSDR, 1995).

Studies of people who drank chlorinated water
showed a possible link between chloroform formed in the water and
cancer of the colon and urinary tract. Animals which received similar
exposures for longer periods of time developed liver and kidney
tumors.

Because chloroform is absorbed rapidly and eliminated
relatively slowly there is concern for chronic and periodic exposures
from ambient air. The presence of chloroform in other media such
as food and water raises concern for multi pathway exposures. The
total dose from all sources of chloroform would need to be taken
into account when considering the health hazard. Because the compound
is metabolized before removal from the body some persons could be
more sensitive to chloroform than the general public. Those of particular
concern would include the young, the elderly, those who are pregnant
and those with liver disease or taking drugs that could affect the
liver.

Chloroform has been classified as Class B2:
Probable Human Carcinogen by the United States Environmental Protection
Agency and as a Group 2B: Possible Human Carcinogen by the International
Agency for Research on Cancer.